Minor improvements to README
Minor improvements to README

Summary: Improve Remarkup formatting.

Test Plan: Eyeball it.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12274

julkiewicz/libphutil,julkiewicz/libphutil,julkiewicz/libphutil